The invention relates to an assembly for remotely and, in an automated manner, taking liquid samples contained in jugs sealed by screw caps or plugs.
The assembly for taking liquid samples according to the invention can, in particular, be used within a tight cell for the analysis of chemical products such as radioactive products moved into said cell in tight jugs. More specifically, the tight cell containing the sampling assembly according to the invention can form part of an automated installation like that described in FR-A-2 675 582. In such an installation, liquid products are sampled in automated manner at different points of a production or processing line and introduced into tight jugs, which are then automatically transferred into analysis units by pneumatic transfer circuits.
In such an installation, the jugs containing the samples to be analyzed drop directly into the bottom of the analysis units. Prior to carrying out the analytical preparation of the samples contained in the jugs, it is consequently necessary for the operators to manually perform, with the aid of handling grippers, three successive manual operations consisting of gripping of a jug, opening the jug then taking a sample from the jug in question. This leads to a certain number of problems which will now be described.
The manual gripping of a jug by the operator with the aid of handling grippers makes it necessary for the operator to search for the jug in the bottom of the analysis unit identifying it by reading a code carried on each jug. In view of the fact that the jugs are loose on the analysis unit bottom, this operation is tedious and difficult. It is further complicated by the optical deformations caused by the inspection window through which the operator reads the codes carried on the jugs. This leads to an error risk and even to the loss of certain jugs, which can lead to the operator requesting a new sampling operation and consequently increases the amount of waste.
In order to open a previously grasped jug, the operator must use two handling grippers. Apart from the difficult nature of this operation, there is a serious contamination risk with respect to the jug content by the grippers and vice versa. In addition and in even more serious manner, the jug opening operation leads to a serious risk of overturning its content in the bottom of the analysis unit. This makes it necessary to call for another jug and leads to an unacceptable time loss. Moreover, the jug content is then directly discharged into the liquid effluents, which is prejudicial to the desired limitations on such effluents.
It should also be noted that the use of handling grippers makes it impossible to seal the jugs, so that the surplus samples not used for the analysis and remaining in the bottom of the jugs constitute waste and cannot be recycled.
Finally, the third operation manually performed by the operator consists of taking a liquid sample from the jug with the aid of a conventional pipette connected by a pipe to a burette located outside the analysis unit. A first disadvantage linked with this operation results from the fact that the operator must read a calibration mark carried on the pipette, which makes it necessary for said operator to be present and represents a long and difficult operation. A second disadvantage is the risk, due to an unsatisfactory manipulation, of passing radioactive liquid to be analyzed outside the analysis unit and into the immediate vicinity of the operator's head.